Kozo Shiranui, known on stage as Yuyama Seijūrō, is an actor with the Yuyama Troupe. His past holds deep tragedy: he faced execution after a policeman framed him for murder. This followed Shiranui's affair with the policeman's wife; the policeman killed his wife and manipulated evidence to implicate him. The troupe's playwright, Sotetsu Ibaragi, secured his freedom by crafting a play that shifted public opinion, leading to Shiranui's release and his eventual membership in the Yuyama Troupe.

Within the troupe, Shiranui performs alongside Ebisu no Zukin, Kakashi no Keishin, and the child actors Kobako and Benimaru. He harbors feelings for Kotoha, a high-ranking courtesan (tayū) at Yokohama's Sekkakurō pleasure house, and maintains a specific fondness for the red-light district. His relationship with Kakashi no Keishin is marked by their similar motivations for joining the troupe, suggesting a bond through shared circumstances. The troupe itself focuses on aiding its leader, Kakunojo Yuyama, in avenging her parents' murder during the Ansei Purges.

Shiranui's involvement places him alongside Yojiro Akizuki, who pursues the supernatural Hasha no Kubi (Head of the Conqueror). However, Shiranui's narrative centers on his role within the troupe's activities and his interpersonal connections, particularly his attraction to Kotoha. Following his rescue, his journey is defined by commitment to the troupe's collective objectives and his integration into their found-family dynamic.